The present invention relates to the control of rotary blood pumps for assisting a failing human heart. More specifically, the present invention relates to the detection of an abnormal condition of an implantable blood pump.
Various types of rotary blood pumps have been developed and are currently under development for use as heart assist devices. Compared to pulsatile pumps, rotary blood pumps have several advantages, including smaller size, higher efficiency, and a simpler design.
However, a servo control system for such rotary blood pumps has yet to be developed. Typically, operators have had to monitor patients in the intensive care unit in order to observe the condition of the pump and the patient, as manual intervention is currently required for controlling the rotational speed of the pump.
If such a rotary blood pump is to be used as a left ventricular assist device (LVAS), the pump flow should be increased when the pressurehead is decreased with the fixed rotational speed of the pump, because these parameters automatically adjust to the patient's physiological condition, regardless of the fixed rotational speed of the pump impeller. However, when the venous return suddenly becomes too low because of physiological changes or overpumping, a high negative pressure may result at the inlet port of the pump, which may lead to a suction condition within the atrium and veins, which may result in serious injury or even death.
In prior art systems, pump flow is typically measured by a flow meter and the position of the impeller of the pump is measured by an ultrasonic sensor.
It would be advantageous to detect an abnormal condition of the pump system without the need for a flow meter or other sensors. It would be advantageous to detect an abnormal condition of the pump system that is derived from power consumption of the pump actuator.
The methods of the present invention provide the foregoing and other advantages.